Liquid pressure mechanism



Oct. 22, 1935 s. SCHNELL 2,018,325

LIQUID PRESSURE MECHANISM Filed Julye, 1932 Il, /l

f n. cHNELL 'O59 I B\ @g 7 Atty.

Patented @ein 229 i asians momo rnsssnaa sinensis;

tion of Delaware Application July 9, 1932, Serial No.. 21,591

1l. Claims.

My invention relates to fluid pressure mechanism and more particularly to improvements in compensating master cylinders for hydraulically actuated brakes. Compensating cylinders now in commercial use have their cylinders in a horizontal position, the reciprocable piston therein being actuated either by an arm on a cross shaft positioned in a reservoir embracing the cylinder end, or by a piston rod extending to the rear of the piston, as for example disclosed in Loughead Patent No. 1,764,179. The latter type of master cylinder is the most economical to manufacture but has the disadvantage of a possible loss of fluid at the rear of the piston due to wear of the secondary packing cup. This disadvantage is not present in the other type of master cylinder but its cost of manufacture is much higher.

One of the objects of my invention is to produce a master cylinder of the compensating type which will have no possibility of leakage and yet be very economical to manufacture. v

Another object of my invention is to produce a generally upright combined master cylinder device including a fluid reservoir which embraces the rear ofthe piston and is formed by a casing which also contains the master cylinder, the piston being actuated by a rod extending through the top of the reservoir.

Other objects will become apparent from the following, description of two embodiments of my invention taken in connection with the accompanying drawing in which Figure 1 is a crosssectional 'View of my improved combined master cylinder and reservoir device mounted upon a. 'motor vehile; Figure 2 is a rear View of the brake pedal and actuating lever; and Figure 3 is a cross-sectional view of a modified form of master cylinder.

Referring to the drawing, l indicates a nonrotatable rod iixedly mounted on the chassis of a motor vehicle and has secured to it a strut or support 2 extending downwardly to a point below and slightly forward of the shaft l. A cupshaped casing member 3 contains a cu -shaped cylinder member il in the lower portion, the rear of the cylinder having bearing on the walls of the casing by means of the flange, as shown. The bottoms of the cylinder and of the cup-shaped casing 3 are secured together by means of a litting member 5 passing through openingsL in the bottoms of the cylinder and the casing. Suitable sealing Washers are interposed between the f1tting member, the casing, and the cylinder, the entire assembly being held together by means of a nut 6 on the inner end of the fitting member.

(Cl. 60m-541i) The cylinder and the casing are pivoted to the lower end of the strut 2 by means of a pivot pin l extending through a portion of the fitting member 5. This fitting member is provided with a central passage 8 connecting the interior of the 5 cylinder with a cross passage 9 which extends into a pair of threaded recesses I0 and l I. These recesses are adaptedto receive the conduits I2 leading to the forward and rear brakes of the Vehicle, the conduits being held in fluid-tight 10 connection with the cross passage 9 by means of the nuts i3.

The casing 3 is provided at its upper end with a'cover member t4 in which is formed a central guide-l5. A piston rod I6 is slidable in the guide 15 and has mounted upon its inner end a piston I1 adapted to reciprocate in the cylinder 4. The piston is provided with the usual packing cup I8 and is held in retracted position by means of a spring i9, the retracted position of the piston 20 being determined by means of a stop 20 secured to the piston rod and cooperating with the inner edges of the guide i5. The upper end of the piston rod carries a clevis 2| for connecting the rod to an actuating arm 22. The arm 22 is piv- 25 oted to the cross shaft l and lies between the bearings 23 of the pivotally mounted brake pedal 2t, also on the shaft l. The pedal 2t carries a short arm 25 overlying the arm 22 and has an adjusting screw 26 cooperating with the lever 22, 30 the adjusting screw 26 being held in the desired position by means of a nut 2l.

In order to prevent dust and dirt from entering the interior of the casing 3 through the guide l5, the piston rod is surrounded by a dust boot 28, one end of which embraces the guide l5 and the other end oi' which embraces the piston rod adjacent the clevis 2l. The cylinder is provided with a compensating port 29 at a point just ahead of the piston cup I8 when the 40 piston is in its retracted position, this port permitting interchange of fluid between the cylinder and the reservoir formed by casing 3 when the piston is retracted. The space surrounding the cylinder is connected with the upper portion of the casing 3 by suitable openings 30 in the flange of the cylinder. The cover M has a plugged opening 3l for filling the casing 3 with a suitable operating fluid.

In operation of my improved master cylinder, the casing 3 is filled with a desired fluid, as is the cylinder t, the conduits l2, and other parts of the braking system (not shown). When it is desired to apply the brakes, the brake pedal is depressed, thereby forcing the piston ll downg5 wardly from its retracted position, as shown, cutting oif compensating port 29 and forcing fluid out of the cylinder through passages 8 and 9 and the conduits I2, thereby applying the brakes. Since the end of the arm 22, which is connected to the piston rod I6, travels in a circular path as it is actuated, the casing and the cylinder will rock about its pivotal connection with the strut 2. This pivotal mounting of the casing 3 insures no binding of the piston and the piston rod. The distance between guide I5 and the piston is such as to prevent any side thrust during actuation of the piston. When the pedal 24 is released, the spring I9 and the pressure exerted on the fluid by the brake releasing springs (not shown), will return the piston to its retracted position as determined by the stop 25.

The arm 22 is shown as provided with an additional clevis pin receiving hole whereby the leverage of arm 22 may be changed if desired. By suitable adjustment of the adjusting screw 26, thel angular relation between the arm 22 and the-pedal 24 can be properly varied to provide for the necessary pedal travel between the released position of the pedal and the floor boards of the vehicle.

The strut 2 between the fixed rod I and pivot 1 oi' the iiuid motor is only under tension and it can be easily designed to be sufficiently strong to prevent any variation in distance between these two points when a high pressure is placed on the pedal.

It is also to be noted that in my improved construction the reservoir for the cylinder is at all times above and embraces the open end of the cylinder and the rear of the piston, thereby preventing allpossibility of air being drawn into the system, and all possibility of any leakage of liquid, there being no joint between relatively moving parts which is required to be liquid tight. The entire structure can be very economically manufactured as the cylinder and the casing may, for example, both be of drawn steel.

Another important feature of my invention is that diiferent size cylinders may be used with the casing 3 without changing the dimensions of the casing due to the spacing of the cylinder from the walls of the casing. 'Ihus it is seen that 'the cylinder and the piston are the only members that need be changed to adapt the master cylinder to different size vehicles. The changing of the cylinder and piston is a very simple matter as the cover I4 and the piston and` piston rod I6 only need be removed to secure access to the nut 6.,

In Figure 3, I have shown my improved master cylinder designed for use where it is desired to have the casing 3 stationary instead of pivoted. In this construction the cover I4' is provided with an enlarged opening for receiving the piston rod I6' which, instead of being directly connected to the piston, as in Figure 1, is connected by means of a ball and socket Joint as shown. The piston I1 is provided with a rearwardly extending circumferential flange for cooperation with the walls of the cylinder in order to more effectively guide the piston within the cylinder walls. The boot 28 embraces a circumferential flange I6 surrounding the opening through the cover Il'., The operation of this structure is the same as thel one previously,` described except that the circular path of the end of the arm 22 when actuated causes pivotal movement oi' the piston rod alone y instead of pivotal movement o! the entire master cylinder.

Having fully described my invention, what l claim as new and desire to secure by Letters Patent of the United States is:

1. In a iluid pressure mechanism, a casing having its axis substantially vertical and a generally l upright cylinder positioned in the lower portion oi' said casing and opening into the upper portion thereof, said cylinder ,being of somewhat smaller diameter than the casing and said open end of the cylinder being provided with a flange l engaging the walls of the casing to position said end of the cylinder therein, and means `for removably securing the bottom of the casing and cylinder together whereby cylinders of varying diameter may be positioned in the casing. 15

2. In 'a :tluid pressure mechanism, a vertically positioned casing, a vertical cylinder in the casing and provided with a ilange at itsupper end spacing it from the walls of the casing, said casing forming a uid reservoir located above the 20 upper end of the cylinder, and a piston reciprocable in the cylinder, said ilange being provided with means for establishing communication between the reservoir and the space between the cylinder and the walls of the casing and said 25 cylinder being in communication with said space when the piston is in its retracted position.

3. In iiuid pressure mechanism, the combination of a support, a reservoir casing, a cupshaped cylinder therein, a conduit tting pivoted 30 to the support and provided with a hollow extension extending through the bottom walls of the casing and cylinder, removable means within the cylinder and cooperating with the extension for securing the casing and cylinder to the 35 extension, and a piston reciprocable in the cylinder.

4. In uid pressure mechanism, the colnbination with a support, of a generally upright cupshaped reservoir casing, a cup-shaped cylinder 40 in the lower part of the reservoir, removable means extending through the bottom walls of the cylinder and reservoir for securing them together. said removable means being provided vwith a passage therethrough. means for pivot- 45 ing said removable means to the support, and a piston reciprocable in said cylinder.

5. In fluid pressure mechanism, the combination with a support, of a generally upright cupshaped reservoir casing, a cup-shaped cylinder 60 in the lower part of the reservoir, removable means extending through the bottom walls of the cylinder and reservoir i'or securing them tcgether, said removable means being provided with a passage therethrough. means for pivoting 55 said removable means to the support, a piston reciprocable in 'said cylinder, and means for establishing communication between said cylinder and said reservoir when the piston is in its retracted position. 0U

6. A master cylinder device comprising a generally upright cup-shaped casing forming/a fluid reservoir, an upright cup-shaped cylinder member positioned in the lower portion of said casing, the top portion of said cylinder being pro- 65 videdwitha ange engaging the inner wall of the casing, a member extending through the bottom walls'of the casing and the cylinder and provided with means i'or removably clamping the bottom of the cylinder to the bottom of the cas- 70 ing, said member being provided with an outlet passagaand a piston reciprocable in said cyl- Inder.

7i. In a'master cylinder device, a pair oi* upright nested cup-shaped members, the inner '55S munication.. between bers at a point in advance oi the piston when the piston is in lretracted position.

8. A master cylinder device comprising a support, a generally upright cup-shaped casing, an upright cup-shaped cylinder positioned in the lower portion of said casing, the top portion vof said cylinder being provided with a ange engaging the inner wall of the casing, a member extending through the bottom walls of the casing and the cylinder and provided with means for removably clamping the bottom of the cylinder to the-bottom of the casing, said member having an" outlet passage therethrough, means for pivoting the member to the support, a piston reciprocable in said-cylinder, and a lever pivoted to the support for actuating the piston. l

9. In a master cylinder device, a support, a pair of upright nested cup-shaped members, the inner cup-shaped member being provided with a ilange engaging the wall of the outer cup-shaped member for spacing the said members apart, a member extending through the bottom walls oi said cup-shaped members for securing them together, said member being pivoted tothe support and provided with an outlet passage, a piston lreciprocable in the inner cup-shaped member, means establishing communication between the inner and outer cup-shaped members at a point in advance oi the piston when the piston is in retracted position, an arm pivoted to the f l 9,018,895 member'being provided'with a perforated the wall oi' the Aouter, member for-spec,-

ing said members apart,means forl removablysecuring the bottom wallsofg-,the members together, aA piston v,reciprociziale:.inv the inner cupshaped member; .and meansestablishing comthe outer and inner mem- "basing, a generally up der positioned inthe lower part o! said casing, a piston in said cylinder, afpiston actuating elev the upper end of the lsupportandeonnectedtothepistomandmeans for operating said arm. v

10. In. hydraulic brake mechanismrthe combination of a generally upright rigid up'"slia.ped ht liquid .pressure cylin- 5 ment reciprocable through the upper end o! the casing, and means at the upper end of said cylinder and engaging the wall of the casing to prevent relative lateral movement'between said -upper end of the cylinder and the casing, said casing extending a substantial distance above the upper end of the cylinder and forming a iiuid containing reservoir for maintaining fluid in 15 contact with the rear of the piston in all of the positions of the piston.

i1. In a fluid pressure mechanism, a generallyv upright rigid casing, a cylinder positioned in the lower part of said casing, means at the upper 20 end of said cylinder spacing said upper endfrom the walls oi said casing, said means also preventing relative lateral movement between Vthe upper end of the cylinder and the casing,- said easing4 forming a uld reservoir located above 25 cylinder and said spacing t means permitting vcommunication between the reservoir and the space between the cylinder and the walls of the casing, a piston reciprocable in the cylinder and provided witha piston rod $0 extending upwardly and beyond the upper end of the casing and reciprocable through said 4upperend, and means establishing communication between the space surroimding the cylinder and the interior of the cylinder when the $5 piston is in its retracted podtion.

STEVE SCHNELL. 

